デカイ | A young people’s word for huge. KIDS$$$ |
巨大 | Huge guy! Like a dinosaur or Gandam. |
甚大 | Gigantic – used about disasters. “The gigantic earthquake killed 1,000 dudes.” NP |
膨大な | Colossal, but not used about physical things. You’d talk about the colossal deficit or budget or a huge amount of data. |